Department News

Condensed Matter Physics

Research Highlight: Bumm Group

The scanning tunneling microscope (STM) provides an atomic view of surfaces with picometer precision. In recent work, graduate student Mitch Yothers working in the Bumm group has demonstrated analytical tools the group is developing to extract statistical information from STM images. The example above starts with a 25 nm × 25 nm atomically resolved image of graphite which contained 11,372 unit cells (not shown). After removing systematic distortion from the image and identifying the location of each atom in the image, the unit cell images can be averaged to produce the averaged unit cell images (gray scale). The standard deviation of the location of the atoms is shown as 1 σ and 2 σ atomic confidence intervals (ellipses).

Research Highlight: Good vibrations

On the top is a model of a carbon nanotube (CNT) to which alkane chains have been attached. Below are “bad” and “good” normal modes for conduction of heat through the system, as calculated by Abdellah Ait-Moussa, a student working with Prof. Mullen. A “bad” mode only couples to atoms in the CNT; a good one couples to the side chains as well as the CNT, so that the vibration and the energy it carries goes through the whole system. The goal of the research is to optimize the side chains to maximize the flow of heat. Improving heat conduction into CNT’s may lead to plastics that conduct heat as well as metals.